Deductive reasoning

In mathematics, if A = B and B = C, then A = C. Since all humans are mortal, and I am a human, then I am mortal. All dolphins are mammals, all mammals have kidneys, therefore all dolphins have kidneys. 

Since all squares are rectangles, and all rectangles have four sides, so all squares have four sides. If Dennis misses work and at work there is a party, then Dennis will miss the party.